CEREBROSPINAL FLUID (CSF)

CEREBROSPINAL FLUID (CSF)

1. By Dr KHALED ALGARIRI CAMS- QASSIM UNIVERSITY October 2019 CEREBROSPINAL FLUID (CSF)

2. INTRODUCTION The cerebrospinal fluid (CSF) is a dynamic,metabolically active fluid surrounding the brain and spinal cord and has many important functions. It is very valuable as a diagnostic aid in the evaluation of inflammatory conditions, infections involving the brain, spinal cord, and subarachnoid haemorrhage .

3. FORMATION OF CSF/ANATOMY Both the brain and spinal cord are covered by three protective membranes referred to as the meninges. The outermost layer is called the dura mater and is composed of tough connective tissue. • The middle layer is the arachnoid named for it spider web like appearance. • The delicate inner most layer which is in direct contact with the brain and spinal cord is called the pia mater . An inflammation of the meninges is referred to as meningitis . 7/

4. FORMATION OF CSF/ANATOMY Between the arachnoid layer and the pia mater is a space called the subarachnoid space . It contains a clear, colorless fluid referred to as Cerebrospinal Fluid (CSF). • CSF is produced in the ventricles of the brain by a collection of rich vascular protrusions called the choroid plexus.

5. Generally, the total volume of CSF circulating throughout the adult Central Nervous System (Brain and Spinal Cord) is approximately 90 - 150 ml. • In newborns this volume is 10 -60 ml. • Excess CSF is continuously reabsorbed by arachnoid villi and returned to the venous system thus maintaining a consistent amount of fluid.

6. FUNCTIONS OF CSF 1-Protection : CSF protects the brain from damage by buffering the brain. It acts as a cushion 2-Buoyancy : The actual mass of the human brain is about 1400 grams; however, the net weight of the brain suspended in the CSF is equivalent to a mass of 25 grams. which allows the brain to maintain its density without being impaired by its own weight

7. FUNCTIONS OF CSF 3-Chemical stability/Homeostasis : CSF maintain the distribution of necessary substance and waste product between CNS and Blood stream 4- Prevention of brain ischemia : made by decreasing the amount of CSF in the limited space inside the skull. This decreases total pressure . transport of biomolecules to the brain • Clearance of catabolites (CO2, lactate) • Maintenance of constant intracranial pressure 5- Clearin of waste: Removes waste from the brain through the bllod for elimination via kidneys.

8. BIOCHEMICAL COMPOSITION OF CSF

9. Examination of CSF (Physical examination) Normal CSF is: Colorless Clear Free of clots Free of blood If CSF is cloudy (turbid)  perform microscopic examination: is usually due to leucocytes may be due to micro-organisms

10. Blood & Hemoglobin pigments in CSF Traumatic tap  bright red color  RBCS in decreasing number as the fluid is sampled Subarachnoid hemorrhage (SAH)  Xanthochromia (hemoglobin breakdown pigments) = RBCs lysis & metabolism previously occurred (at least 2 hr earlier)

11. CSF glucose test A CSF glucose test measures the amount of sugar (glucose) in the cerebrospinal fluid (CSF). CSF is a clear fluid that flows in the space surrounding the spinal cord and brain .

12. Normal Values The glucose level in the CSF should be 50 - 80 mg/100 mL (or greater than 2/3 of the blood sugar level). Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results

13. Abnormal CSF [Glucose] ↑ CSF [glucose]: Not clinically informative Provides only confirmation of hyperglycemia

14. ↓CSF [glucose] (hypoglycorrhachia ): Disorder in carrier-mediated transport e.g. TB meningitis Active metabolism of glucose by cells or organisms: e.g. acute purulent, amebic, & fungal meningitis Increased metabolism by the CNS e.g. by CNS neoplasm In viral meningitis CSF [glucose] is usually normal

15. CSF/blood glucose ratio Normal CSF glucose / plasma glucose ratio is approximately 0.6-0.7 (N.B. Ratio is decreased if plasma glucose is more than 500 mg/dl due to saturation of the glucose carrier system to CSF CSF/blood glucose ratio may be a better single indicator for bacterial meningitis. Since the CSF glucose and blood glucose values are promptly and easily obtained from a lumbar puncture

16. Protein in CSF Proteins , mostly albumin are found in the CSF (0.15-0.45 g/L) Source of CSF proteins: 80% from plasma by ultrafiltration 20% from intrathecal synthesis

17. ↑ CSF [total protein]: Must be compared to the serum [protein] Useful nonspecific indicator of pathological states: Lysis of contaminant blood (traumatic tap) ↑ premeability of the epithelial membrane due to: Bacterial or fungal infection Cerebral hemorrhage ↑ production by CNS tissue in: Multiple sclerosis (MS) Subacute Sclerosing Panencephalitis (SSPE ) Obstruction e.g. in: Tumors Abscess

18. Albumin in CSF Albumin is produced solely in the liver Its presence in CSF must occur through BBB Measured by the protein electrophoresis method

19. CSF Immunoglobulin CSF IgG can arise: from plasma cells within CSF from the blood through BBB ↑ [ IgG ] and normal [ Alb ] of CSF suggests local production of IgG , e.g., Multiple sclerosis (MS) Subacute sclerosing panencephalitis (SSPE)

20. CSF LACTATE In neonates (10-40mg/dl) . In adult or older children (10-22 mg/dl) Measurement of lactate concentrations in cerebrospinal fluid (CSF) may be useful as part of the investigation of inborn errors of metabolism in which lactic acidosis occurs . This includes disorders of gluconeogenesis, pyruvate dehydrogenase complex, the Krebs cycle and the mitochondrial electron transport chain. Levels greater than 35 mg/dl are frequently seen with bacterial meningitis (due to increased glycolysis by bacteria & inflammatory cells), whereas in viral meningitis, lactate levels remain lower than 25 mg/dl.

21. CSF LACTATE cont CSF lactate levels remain elevated during initial treatment but fall rapidly when treatment is successful, thus offering a sensitive method for evaluating the effectiveness of antibiotic therapy. Measurement of lactate in CSF has also been advocated for investigating children with unexplained neurological disease

22. Otorrhea & Rhinorrhea Otorrhea : leakage of CSF from the ear Rhinorrhea : leakage of CSF into the nose

23. CSF GLUTAMINE Normal range 8-18 mg/ dL Glutamine is produced in the CNS by the brain cells from ammonia and alpha- ketoglutarate . This process serves to remove the toxic metabolic waste product ammonia from the CNS. Glutamine synthesis helps to protect the CNS from the toxic effects of increased ammonia . Ammonia production is increase dramatically in patients with liver failure . Accordingly, CSF glutamine production is increased in cases of hepatic encephalopathy

24. CSF ENZYMES Lactate dehydrogenase LDH – LD1, LD2, LD3, LD4, LD5 -Increase LD5 in metastatic brain tumor. -Increase all fractions in primary brain tumor such as Meningioma ( extra- exial ) Glioblastoma (intra – exial ) -Increase LD4,LD5 in bacterial meningitis.

25. CSF ENZYMES CK – BB: - Increase in: epileptic patient Brain tumor cerebral infarction

26. CSF ENZYMES CSF adenosine deaminase (ADA ) elevations can occur in tuberculous meningitis.

27. Other Chemical Components of CSF CSF [Calcium], [Potassium] & [Phosphates] are lower than their levels in the blood CSF [Chloride] & [Magnesium] are higher than their levels in the blood Abnormal CSF [Chloride] marked  in acute bacterial meningitis slight  in viral meningitis & brain tumors

28. How the Test is Performed LUMBAR PUNCTURE A lumbar puncture is a medical procedure where a needle is inserted into the lower part of the spine to test for conditions affecting the brain, spinal cord or other parts of the nervous system

29. CSF is collected by lumbar puncture between third, fourth, fifth lumbar vertebrae. It requires certain precautions and careful technique to prevent the introduction of infection or the damaging of neural tissue. Lumbar puncture

30. Risk Factors

31. CSF is collected in three sterile tubes Tube 1 – used for chemical and serologic test: centrifuge and use supernatant for chemistry analysis (glucose, protein, enzymes and chloride)\ kept in freezer till performed. Tube 2 – used for microbiology lab\ kept in room temperature Tube 3 – used for hematology (cell count) Cell counts done as soon as possible after the fluid is collected as cellular degradation occurs rapidly. If postponed, refrigerate for up to one hour .